This invention relates to wastewater treatment systems and improvements thereto. More particularly, this invention relates to an apparatus for treatment of primary effluent from residential and commercial establishments to allow subsurface or surface disposal of wastewater therefrom.
Many areas in this country are experiencing an increase in population accompanied by a larger demand for housing and commercial establishments in rural areas and around major municipalities with no access to a public sewer system. Conventional onsite wastewater systems provide a viable option for managing the wastewater generated by development, however, not all soils are suitable for these systems. Conventional onsite wastewater systems also require a large land area, putting a premium cost on real estate in many locations. In order to maintain a non-hazardous environment, residential and commercial establishments must treat wastewater that they produce. Since public utility wastewater treatment systems and conventional onsite systems are not always available or are not desirable, alternative wastewater treatment methods are often necessary. Due to the premium price on real estate and the high density of residential and commercial building, it is desirable to reduce and minimize the space required for wastewater treatment systems to treat the wastewater to acceptable standards.
Single layer recirculating media filters are currently available as site-built systems utilizing separate structures for recirculation basins, filters and dosing tanks. These distributed systems need large areas for treating wastewater to acceptable standards and require knowledgeable, trained, designers and installers. Intermittent (single pass) filter media systems are also available as site-built systems, however, they require up to five times more area and typically do not attain the level of treatment of recirculating media filter systems.
The level of treatment a system can achieve is directly related to the surface area of filter media available to the system and the number of times that the wastewater is passed through the available filter media.
Accordingly, a need exists for a wastewater treatment system that can treat wastewater to acceptable standards, does not require a large amount of ground area, and can be installed using simple construction techniques.
The present invention is a self contained wastewater treatment unit designed to reduce the levels of biochemical oxygen demand, total suspended solids, ammonia, nitrates, and pathogens in the influent to the wastewater treatment unit. The wastewater treatment unit preferably follows a septic tank or other system which provides primary treatment which includes separation of solids from the liquid portion of the wastewater. The wastewater treatment unit will treat the influent wastewater to allow subsurface or surface disposal of the treated effluent wastewater. The effluent from the wastewater treatment unit can be disposed of using conventional gravel distribution trenches, subsurface drip irrigation, or surface discharge depending on the local regulations.
A wastewater treatment unit according to the present invention includes a recirculation chamber, a dosing chamber having no direct fluid connection to the recirculation chamber, and at least two filter layers in a single tank. Each filter layer containing filter media and being located above the recirculation and dosing chambers. The wastewater treatment unit also including an influent pipe, a recirculation pump located in the recirculation chamber, a recirculation valve, an optional dosing pump in the dosing chamber, and an effluent discharge pipe connected to the dosing chamber. The influent pipe directs wastewater entering the wastewater treatment unit into the recirculation chamber, the recirculation pump pumps the wastewater from the recirculation chamber onto the filter layers; the wastewater flows through the filter media of the filter layers and is directed back to the recirculation or the dosing chamber; and the wastewater is discharged from the wastewater treatment unit through the dosing pump and effluent discharge pipe. Baffles can be inserted in the recirculation and/or the dosing chamber to create flow paths through the respective chamber(s).
One advantage of the present invention is that it has multiple layers of aerobic filter media in a single structural tank. The multiple filter media layers reduce the footprint necessary for the wastewater treatment system by a factor of the number of layers in the unit. A two-layer filter system requiring one-half the footprint of a single layer filter system; a three-layer filter system requiring one-third the footprint of a single layer filter system; and so-on.
Another advantage of the present invention is that it has separate recirculation and dosing chambers in a single structural tank. The separate recirculation and dosing chambers improve the level of treatment that can be achieved by the wastewater treatment unit.
Another advantage of the present invention is that it is a self-contained package unit assembled in a single tank. This package concept allows relatively unskilled contractors to install a complex treatment system without the need of professional engineering services.
Yet another advantage of the present invention is it allows for design standardization which can be used to simplify the regulatory approval process. The treatment capacity and footprint of the wastewater treatment unit being known allows for a known amount of ground space to be allocated to obtain the necessary wastewater treatment levels.
Additional objects, advantages and novel features of the invention are set forth in the description that follows, and will become apparent to those skilled in the art upon reviewing the drawings in connection with the following description.